1. Field of the Invention
The present invention relates to a reproducing apparatus for reproducing a field-recorded video signal.
2. Description of the Related Art
In a video signal reproducing apparatus which reproduces a video signal formed by recording only either one of fields constituting one frame of video signal, as in the case of field recording adopted by a still video system, it is common practice to perform the processing of alternately outputting a recorded field signal and a signal, which has been line-interpolated by a 1H (horizontal scanning line) delay line, at intervals of one vertical scanning period in order to prevent a flicker (luminance fluctuations which are visually perceived in a vertical direction).
A circuit of the type shown in FIG. 1 has conventionally been used as a circuit for effecting the above-described interpollution processing. FIG. 1 is a block diagram schematically showing one example of a reproduced signal processing circuit for a still video system.
The circuit shown in FIG. 1 comprises an input terminal 1 for receiving a luminance signal Y+S which has been reproduced, an input terminal 2 for receiving a select signal HOKAN for selecting a field to be interpolated or a field not to be interpolated, an input terminal 3 for receiving a color-difference line-sequential signal (R-Y/B-Y) which has been reproduced, an input terminal 4 for receiving a control signal LINE for effecting simultaneous conversion of such a color-difference line-sequential signal, and input terminals 5 and 6 for respectively receiving subcarrier signals FSC0 and FSC90 having phase angles of 0.degree. and 90.degree. which are used for quadrature two-phase modulation of a chrominance signal.
The luminance signal inputted through the input terminal 1 is applied to a 1H delay line (1H DL) 7, and also to an adder 9 as well as to a terminal b of a switch 10. The signal having passed through the 1H delay line 7 is applied to a low-pass filter (LPF) 8, where a clock component is eliminated from the signal. Thereafter, the signal is inputted to the adder 9. In the adder 9, the input signal is added to the luminance signal inputted from the input terminal 1 to form a line-interpolated signal. The line-interpolated signal is applied to a terminal a of the switch 10. The switch 10 is alternately switched at intervals of one vertical scanning period by the select signal HOKAN. If the switch 10 makes connection with the terminal a, the interpolated signal is inputted to an adder 11, while if the switch 10 makes connection with the terminal b, the non-interpolated signal is inputted to the same. In consequence, interpolated and non-interpolated signals are alternately selected and inputted to the adder 11 at intervals of one vertical scanning period.
In the meantime, the color-difference line-sequential signal inputted through the input terminal 3 is applied to a 1H (horizontal scanning line) delay line (1H DL) 13 and also to a terminal e of a switch 15 as well as to a terminal g of a switch 16. The signal having passed through the 1H delay line 13 is applied to a low-pass filter (LPF) 14, where a clock component is eliminated from the signal. Thereafter, the signal is applied to a terminal d of the switch 15 and to a terminal h of the switch 16. Each of the switches 15 and 16 is switched at intervals of one horizontal scanning period by the control signal LINE inputted through the input terminal 4 so that a color-difference signal R-Y and a color-difference signal B-Y are successively outputted through a terminal f and a terminal i, respectively. The color-difference signals R-Y and B-Y are inputted to a modulator (MOD) 17. The modulator 17 modulates the color-difference signals R-Y and B-Y by using subcarriers which have respectively been inputted through the terminals 5 and 6, and forms a quadrature two-phase modulated signal by addition. The quadrature two-phase modulated signal is supplied to a band-pass filter (BPF) 18, where an unwanted component is eliminated from the signal. Thereafter, the signal is supplied to the adder 11, where it is added to the aforesaid luminance signal to form a composite signal. The composite signal is outputted through an output terminal 12.
The above-described conventional example uses the 1H CCD delay line 7 for the purpose of interpolating a luminance signal and, in addition, the 1H CCD delay line 13 for the purpose of effecting simultaneous conversion of a color-difference line-sequential signal, whereby the luminance signal and the color-difference signal are each delayed by one horizontal scanning line. Such a CCD delay line is small compared to a glass delay line and has a number of advantages such as a small distortion and a wide frequency band. However, the CCD delay line has two disadvantages: large power consumption and clock noise. These disadvantages have made it difficult to adopt the circuit of FIG. 1 for products of reduced size and power consumption.